This invention relates to an engineering constructive load cell and more particularly to an improved load cell used to measure the weight of a load. The load cell is used in combination with an anchored bolt and a wall or an obstruction board which prevents any soil or sand from overflowing at an engineering construction site.
A prior art engineering constructive load cell, illustrated in FIGS. 8 and 9 is formed by use of an anchored bolt 37 which extends through an obstruction board 35 with a thin cylindrical elastic body 32 secured on the end of the bolt that protrudes through the obstruction board between a supporting pipe and a nut 38. Electrical strain gauges 33 are secured to the cylindrical surface of the elastic body and connected to an electrical circuit which measures a load placed on the elastic body by a load against the obstruction board. The strain placed on the strain gauges is a measure of the load placed on the obstruction board.
in a prior art load cell, illustrated in FIG. 9, a thin cylindrical elastic body 32 is sandwiched between a spool-like support placed against the obstruction board 35 and a shoulder on a nut 38 threaded on the bolt 37 which is anchored in a cement base 36. The obstruction board and elastic body is then fixed in place by the nut. As a material is placed in the area between the cement anchor and the obstruction board a compression strain is placed on the elastic body 32. Strain gauges placed on the thin cylindrical body are placed under a strain which changes the resistance of the strain gauges to a current flow. The load against the obstruction board as measured by current flow is a measure of the strain on the elastic body which is equated as load by an attached electrical circuit which is well known in the prior art.
In the prior art load cell the elastic body must be made thin so that the load on the elastic body causes a strain in the surface which can be measured by the strain gauges.
In the prior art device the cross sectional area of the elastic body has been made very thin so that the stress or strain on the elastic body will produce a large strain value. Making the elastic body thinner weakens the body so that under heavy loads the body will buckle which prevents obtaining an accurate load. Applicant has determined that when elastic bodies are made thinner to obtain greater sensitivity it can only be used for small loads to avoid buckling.